1. Field of the Invention
The present invention relates to a viscous heater, wherein a viscous fluid is subjected to a shearing force to generate a heat which is used as a heat source which is subjected to a heat exchange with a heating medium recirculated to a heating system.
2. Description of Related Art
A Japanese Unexamined Patent Publication No. 2-246823 discloses a viscous heater used for a heating system for a vehicle. The viscous heater includes a front and a rear housing, which face each other and are connected by means of bolts, while a heat generating chamber and a water jacket are formed between the housings, so that the water jacket is located outside the heat generating chamber. Provided in the water jacket is an inlet for taking in the recirculated water into the water jacket and an outlet for discharging the recirculated water after subjected to a heat exchange into the heating system. A drive shaft is rotatably supported to a housing by means of a bearing unit. Connected to the drive shaft is a rotor, which is arranged in the heat generating chamber, so that the rotor is rotated in the heat generating chamber. Furthermore, a gap is formed between the inner surface of the heat generating chamber and the outer surface of the rotor, and a viscous fluid, such as a silicone oil, is filled in the gap.
However, in the viscous heater in the prior art, the heat generating chamber as well as the water jacket as the heat emission chamber are formed only by the front and rear housings as one piece members respectively. As a result, the front and rear housings have complicated shapes, which increases the production cost of these parts.
Furthermore, in the viscous heater in the prior art, the inner wall of the heat emission chamber has a relatively small surface area, resulting in a reduced value of the heat exchanging efficiency. Furthermore, a measure is not provided as far as problems such as a leakage of the viscous fluid and a thermal degradation of parts made from a non-metallic material are concerned.
In view of the above, in order to improve productivity, separate members can be used for forming a heat emission chamber in such a manner that, between the members, the front and rear housings for constructing the heat emission chamber are simply connected. However, this structure is disadvantageous in that the number of contacting surfaces, which necessitate water seal members, is increased. Furthermore, an increased precision is required in order to obtain a desired anti-water leakage property.